A 2-year-old Honduran asylum seeker cries as her mother is searched and detained near the U.S.-Mexico border on June 12, 2018 in McAllen, Texas. The asylum seekers had rafted across the Rio Grande from Mexico and were detained by U.S. Border Patrol agents before being sent to a processing center for possible separation.

(John Moore/Getty Images)

A doe-eyed girl stands on crutches — her right leg is gone. Rows of people cling to the roof of a train. A handcuffed couple gently holds hands. A dead body lies on the ground. A throng of new citizens recites the Pledge of Allegiance.

Undocumented Guatemalan immigrant Elvira Lopez, 22, stands on crutches at the Jesus el Buen Pastor shelter on July 31, 2013 in Tapachula, Mexico. She fell under the wheels of a freight train and lost her right leg while on route to the United States. The image appears in Undocumented: Immigration and the Militarization of the United States-Mexico Border.

(John Moore/Getty Images)

These are the subjects of just a few of the many images taken by photojournalist John Moore in his new book, Undocumented: Immigration and the Militarization of the United States-Mexico Border (PowerHouse, $50), which he'll be discussing Friday at Deep Vellum Books in Dallas.

John Moore, with his book Undocumented

(

Hector Vivas

/Getty Images)

Moore, who grew up in Irving and graduated from the University of Texas at Austin, started working on the book about 10 years ago. When he returned from the Middle East in 2008 after witnessing the assassination of former Prime Minister Benazir Bhutto of Pakistan, his work for Getty Images took him to the border area. He was based in New York.

"In my early trips to the border, I was impressed with this dramatic human story of people seeking a better life against all odds," Moore said in an interview Friday from New York.

Then, the drama increased. In 2010, Arizona had just passed a strict anti-illegal immigration law, which caused lots of protests.

"I could see the beginning of a movement in the U.S. and the fear by many Americans of undocumented immigrants," Moore said.

Tensions flared even more when President Donald Trump was elected. These developments led to the idea of publishing a book of photos and text that tells the story of illegal immigration from all sides.

A man looks through the U.S.-Mexico border fence into the United States on September 25, 2016 in Tijuana, Mexico. Friendship Park on the border is one of the few places on the 2,000-mile border where separated families are allowed to meet.

(John Moore/Getty Images)

Undocumented immigrants comfort each other after being caught by Border Patrol agents near the U.S.-Mexico border on April 13, 2016 in Weslaco, Texas.

(John Moore/Getty Images)

A group of young men walk along the Mexican side of the U.S.-Mexico border fence in a remote area of the Sonoran Desert on December 9, 2010 in the Tohono O'odham Reservation, Arizona.

(John Moore/Getty Images)

U.S. Border Patrol agent Sal De Leon stands near a section of the U.S.- Mexico border fence while stopping on patrol on April 10, 2013 in La Joya, Texas.

(John Moore/Getty Images)

Undocumented Guatemalan immigrant Elvira Lopez, 22, stands on crutches at the Jesus el Buen Pastor shelter on July 31, 2013 in Tapachula, Mexico. She has been convalescing at the shelter for six months after falling under the wheels of a freight train and losing her right leg while on route to the United States.

(John Moore/Getty Images)

Families attend a memorial service for two boys who were kidnapped and killed on Feb. 14, 2017 in San Juan Sacatepequez, Guatemala. More than 2,000 people walked in a funeral procession for Oscar Armando Top Cotzajay, 11, and Carlos Daniel Xiqin, 10 who were abducted walking to school Friday morning when they were abducted.

(John Moore/Getty Images)

A Mexican immigrant family sits in the living room of their rented home on April 24, 2010 in Tuscon, Ariz.

(John Moore/Getty Images)

"I had been photographing immigration as part of my daily news reports for Getty Images and had been trying to cover immigration from as many different angles as possible," Moore said. "It was only with the election of Trump that we decided to put this together in book form."

The immigration issue has divided the United States since the country was founded. Moore mentions in his book how President Dwight Eisenhower in the 1950s ordered the deportation of more than a million Mexicans.

To look at the issue today, Moore writes in his book that he has "driven, flown over and floated down the entire length of the U.S.-Mexico border." He traveled extensively throughout Central America and Mexico, as well as to many U.S. immigrant communities. His photos tell the stories of not only immigrants, but also border agents, assassins in Honduras, gang members, prisoners and detainees.

He faced danger, but knowing Spanish helped. He learned it early on in his career when he was based in Nicaragua for two years and then Mexico City for 5 1/2 years. He also had a "fixer."

"When working in a hostile environment in Honduras, I worked with a local journalist [his fixer] who knew the assassins," Moore said. "He helped me get the photos I needed and get out of the situation safely." Moore was able to photograph a crime scene without reprisal, as well as assassins with only their eyes peering through from faces wrapped in scarves.

One of his goals with the book was to show the root causes of why immigrants want to flee their homes.

"For me, it's been important to humanize the story," Moore said. "Americans oftentimes concentrate on the statistics so much — for example, 11 million undocumented immigrants living in this country. Those are 11 million people with different stories and reasons to come to this country."

The stories are heartbreaking. One photo shows a man who was deported from Des Moines, Iowa, weeping next to a shack where he now lives. Another depicts grieving mothers holding photos of sons who were kidnapped.

A man looks through the U.S.-Mexico border fence into the United States on September 25, 2016 in Tijuana, Mexico. Friendship Park on the border is one of the few places on the 2,000-mile border where separated families are allowed to meet. The image appears in Undocumented: Immigration and the Militarization of the United States-Mexico Border.

(John Moore/Getty Images)

In the book, Moore writes, "Endemic poverty continues to fuel emigration from Central America. However, in recent years, increased violence also drives large numbers of people from their homes."

Shifting to the north side of the border, Moore visited the U.S. Border Patrol Academy in Artesia, N.M., just as a group of recruits arrived for boot camp.

"I spent so much time with these agents as they tracked smugglers and tried to treat them and all the groups in the book with respect," he said.

Moore also covered the border from the air. From his helicopter rides, he captured the sweeping natural beauty of the region.

His book ends with cheerful photos of a naturalization ceremony.

"It's one of my favorite events to cover," he said. "It's a joyous occasion when immigrants are able to work through the system and finally become U.S. citizens."

In the book's forward, which is written in English and Spanish — as is all text in the book —NPR correspondent Tom Gjelten writes, "Moore does not tell us what he thinks of the immigration policies whose consequences he documents. This is a book of photography, beautiful in its imagery, powerful in its intimacy. The idea is only that we encounter the people affected and the graphic reality of their experience. "